Our overall objective is to elucidate the mechanisms that regulate gene expression at the level of transcription in the mammalian cell, and, in particular, the mechanisms that regulate alpha-fetoprotein (AFP) gene transcription during ontogenesis and hepatocarcinogenesis. Current evidence indicates that the nonhistone chromatin proteins regulate gene transcription in eukaryotes; however, the mechanism of action of these proteins as gene regulators is not yet resolved. Our first objective is to determine if the differential expression of the AFP gene(s) observed during cytodifferentiation and hepatocarcinogenesis involves a change in the template specificty of the cell's chromatin and to identify the chromatin proteins that affect AFP gene transcription. The mRNA for AFP will be isolated and DNA complementary in base sequence (cDNA) to this RNA prepared. The AFP specific cDNA probe will be used to detect the in vitro transcription of AFP gene specific sequences from chromatin prepared from fetal and adult rat liver and hepatomas by RNA/cDNA hybridization. Chromatin reconstitution experiments will be performed to identify the chromatin proteins that regulate AFP gene transcription. Additionally, the AFP-cDNA probe will be used to determine the role that chromatin reconstitution plays in regulating specific gene expression the length of time required for the reinitiation of AFP gene transcription following stimulation of quiescent cells, and the mechanism of the suppressive effect of glucocorticoids on AFP expression. A long-term goal of this project is to elucidate, at least in part, the nature of the biochemical mechanisms that regulate gene expression in embryonic development and malignant transformation.